


Broken Promises

by xxashleyxx



Category: Supergirl (TV 2015)
Genre: Angry Mon-El, Angst, Angst and Hurt/Comfort, Angst with a Happy Ending, Comfort Sex, Confused Kara, Disappointed Mon-El, F/M, Hurt Mon-El, Hurt/Comfort, I Love You, KaraMel, Making and Breaking Promises, Not Episode Related, Risk Taker Kara, Sad Mon-El, Sex, Smut, Worried Mon-El, kryptonite bomb
Language: English
Status: Completed
Published: 2017-04-22
Updated: 2017-04-22
Packaged: 2018-10-22 11:16:07
Rating: Mature
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 4,186
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/10695885
Author URL: https://archiveofourown.org/users/xxashleyxx/pseuds/xxashleyxx
Summary: "He’d never felt this much anxiety, this much fear before, and definitely not while on Earth with his superpowers. Superpowers. He stood there next to her and even with all his powers, there was nothing he could do." -- Kara promised Mon-El that she wouldn't go and try to diffuse the Kryptonite bomb. Mon-El can't believe she broke her promise.





	Broken Promises

**Author's Note:**

> Hi all! Thanks for dropping in to read another one of my fics. Be prepared, this one is a little angsty!
> 
> Note that I actually had about half of this fic written before 2x16: Star-Crossed, but I guess the writers just beat me to the ILY. So let's all just pretend that Mon-El's confession of love in 2x16: Star-Crossed didn't happen, but we're still at around the same timeline in their relationship. I also know nothing about the making or diffusing of Kryptonite bombs, so just work with me here.

They had all told her not to go.

_Every single one of them._

The agents at the DEO. J’onn. Alex. James. Winn. Mon-El.

It was far too dangerous. Somehow they had managed to get a hold of Kryptonite -- some angry human that had no idea what they were doing. They had created a Kryptonite bomb and planted it in the city, set to explode in two days. It was still so early on in the investigation; they didn’t have enough details to figure out how to go about destroying or disassembling it.

What they did know was that they had _time_.

That might sound weird considering it was a bomb, but from what they could tell so far, it was very crude; rudimentary, and likely not a fully functioning bomb at all.

Since it was made with Kryptonite, the DEO tech was able to find it easily when they were scanning for radioactive materials. They scanned a lot of areas before sending Kara out on a mission nowadays. Because of some basic, everyday precautionary scanning, they now had two whole days to figure out how to disarm the device and prevent any possible explosion. What they really feared was that the bomb would release a Kryptonite gas or create an explosion that was bigger than what they had predicted, the bomb somehow disguised as being poorly manufactured when really it was skillful and dangerous. _Especially dangerous to Kara_.

This uncertainty was why they needed _more time_. They had two whole days to work. They weren’t just going to send Kara into that mess. Not if Kryptonite was involved, that’s for sure.

_“I have to go!” Kara insisted. “I have to stop it before it goes off. It’ll hit too large of an area, J’onn!”_

_“Kara, we have two days to figure this out. We’ll get there. I’m not sending you into a battle you wouldn’t come back from. We don’t know how bad it will be. We don’t even know how to disarm it!” J’onn shook his head at her. He wasn’t risking her life on this._

_“We’ve disarmed bombs before, Kara,” Alex reminded her. “We’ll do it again. You just need to relax while we try to figure this out.”_

_“Relax, Alex? How am I supposed to relax when thousands of lives are at risk here? Why can’t we just tell people about the bomb and evacuate?”_

_“That’ll cause panic and chaos,” J’onn jumped in. “We can’t give them that information right now. For one, we don’t even know if it’s a fully functioning bombing device. Secondly, for all we know, the bomber could change the detonation time on us and we could make this whole thing worse.”_

_“J’onn--”_

_“Kara, we have other agents who can handle this. I’m not putting you in danger like that and that decision is final.”_

_“And what’s to stop me from running off and doing this alone?”_

_“I’m ordering you not to, Kara,” J’onn’s voice was stern._

_“And I’m not letting you,” Mon-El stepped up to her._

_She spun around to face him. “I’m sorry? You’re not_ letting _me? I don’t need you to_ let _me do anything.” Kara was up in his face now and he gently put his hands on her shoulders._

_“Kara,” he started. “I know you want to help people, but you can’t help people if you run in there all upset before we have a handle on this. We need to stop and figure this out. We need to be careful. This is Kryptonite we’re talking about. We can’t have anything happen to you.” He swallowed the lump forming in his throat. “I can’t--” the words wouldn’t leave his throat as he looked back at her._

_She looked into his eyes and she could see that he was tearing up. She closed her own with a sigh, “Mon-El,” she whispered, “I can’t just sit here…”_

_“You’re not,” he insisted. “You’re helping figure this out like the rest of us. A little bit of time. That’s all we need.”_

_She stared up at him._

_“Kara,” his voice became stern as he attempted to blink away the tears in his eyes. “I need you to promise me.”_

_She searched his eyes, “Promise you what?”_

_“You know what,” he stated, his hands coming up to cup her cheeks. “I need you to promise me that you won’t go out there by yourself. That you won’t get anywhere_ near _this bomb until we figure out how to fix this.”_

_She blinked at him. His grip on her face tightened._

_“Kara!”_

_“Okay, okay, fine. I promise.”_

_“You promise…?”_

_She rolled her eyes. “I promise I won’t go out there alone and I won’t go anywhere near the bomb. Happy?”_

_“Yes, very,” he nodded. “Thank you.” He pecked her lips lightly before brushing her hair behind her shoulders with his fingertips. “Now,” he spun her body around. “Let’s get back to work.”_

Then at T-Minus 32 Hours, she broke her promise.

She went off by herself, found the alleyway that the bomb was being hidden and she flew out there while everyone was busy looking over the wire structure of the countdown clock. She made it all the way to the site before anyone wondered where she was.

Mon-El had noticed first. They’d gone out to lunch and he hadn’t seen here since they got back to the DEO almost an hour ago. He went to ask Alex if she’d seen her. He stood over Alex’s shoulder watching the screen in front of her as he asked.

They had hacked into some cameras already on site and they were assisting the team in analyzing the best way to go about disarming the bomb when Alex thought that she saw Kara appear in the distance. Just a set of familiar red boots at the top corner of their camera view. She called out for Winn to zoom in.

While they were busy going over whether or not that was actually Kara at this distance, in a flash she was in front of the bomb, cringing as she reached for the wires.

They had gone over what would happen if you pulled each of the bomb’s wires: individually, in pairs, in threes, altogether. They were leaning towards all wires being pulled at once because of its crude nature, thereby disconnecting from the countdown clock and the explosive aspects of the bomb simultaneously and not giving any part of the contraption the opportunity to send the signal to explode. They were _leaning_ , not positive. _Nowhere near positive._

But there was Kara, standing in the alleyway, stepping closer to the bomb and pulling all the wires at once. By the time Winn and Alex realized it was Kara and what she was doing, Mon-El had already dashed out of the DEO, headed toward the bomb’s location. But she was already pulling those wires and even with his superspeed, he wasn’t going to make it in time to stop her.

Mon-El had arrived on the scene just as a green tinted gas erupted upwards into the sky: dark, cloudy and terrifying. The ground shook, but just barely, the explosion small enough that it really didn’t leave the alleyway. Clearly it was as suspected; that the bomber had no idea what they were doing. But he saw her body fly, the Kryptonite explosion strong enough against Supergirl as if it were any giant explosion against a human being.

Mon-El dove at her body as he saw her hit the ground, barely stopping her head from bouncing dangerously against the asphalt as she went limp.

He had never been so scared in his entire life.

His arms wrapped around her as he picked her up from the ground, holding her body tightly to his chest. His fingers were to her neck as he felt an extremely faint pulse, and through his tears, he wasn’t sure if he could see her breathing, her chest barely rising and falling, if at all.

He rushed her back to the DEO where the agents took her body from his arms, rushing her into the med bay and proceeding to check her vitals. He was _almost_ sure she was breathing, but she hadn’t woken up, even once she was taken away from the Kryptonite. Her eyes hadn’t fluttered. Her arms hadn’t moved.

“Kara,” he breathed, as the agents started to shove him aside so they could figure out what to do to help her.

The backs of his hands scraped against his cheeks as he wiped at the tears spilling from his eyes. His heart was pounding in his chest and his legs were tingling; he could barely stand next to the examination table they had laid her down on. He felt his head spinning. He was pretty sure he was going to pass out. He’d never felt this much anxiety, this much fear before, and definitely not while on Earth with his superpowers.

Superpowers.

He stood there next to her and even with all his powers, there was nothing he could do.

* * *

It had been _two days._

As soon as her eyes had opened, she had seen him. He was sitting there on a stool, similar to the way she had sat there in the same spot what felt like so long ago when he was sickened by the Medusa virus. His eyes were blank and staring off into the distance. When he’d noticed that her eyes had opened, his face was surprised; his eyebrows raising as he abruptly stood from the stool and almost sent it crashing to the floor. She opened her mouth and tried a _Mon-El_ , but the words couldn’t come out; her throat too dry.

Then he left the room. He didn’t even say anything. He just ran out.

Seconds later, dozens of people ran in. Some checking her vitals, Alex close behind them, tears in her eyes as she welcomed Kara back to consciousness.

All of the agents were there. They had all gathered in the DEO med bay and insisted that they were happy that she was okay. They had all told her that they were just worried about her health and her safety. They were all glad that she had woken up and come back to them.

Mon-El spent the entire time standing in the corner of the room, far behind the crowd around her, making this _face_. This face that Kara didn’t recognize on him. It wasn’t angry. It wasn’t sad. Disappointment, maybe? She didn’t understand why. She had to go after that bomb. She needed to protect the city. Didn’t he understand that? She had done it for the people of National City.

Her vitals were strong. She looked to be back to her usual strength, the simulated yellow sun rays bringing the colour back to her face. Alex told her to take it easy, stay off the Supergirl duties for a few days while they handle the city for her. Go home. Relax. Take care of herself.

The crowd had cleared from the room, everyone quickly getting back to work. Everyone except Mon-El who continued to stand off in the corner. The first (and only) words he spoke: “I’ll take you home.”

* * *

Kara walked into the apartment, the only sound being her heeled boots thumping against the floorboards. He hadn’t said anything on the way over and she knew he was upset. She could see it in his eyes, in his clenched jaw.

She walked to the table, setting down her things before she turned to look at him. His hands were in his pockets, his eyes downcast.

“Aren’t you going to say anything?” she asked suddenly, her voice annoyed as his head rose, his eyes catching hers.

“Excuse me?”

“You’ve said four words to me since I woke up. Aren’t you going to say anything else? Anything like, ‘I’m happy you’re okay’ or ‘that was stupid of you, Kara’. Anything?” He blinked back at her. “Anything at all, Mon-El. I can see you’re upset. Please, just say something.” His eyes bore into hers.

“You broke your promise.”

She stared back at him, “I…what?”

He stepped toward her, his shoulders square, his eyes now angry, “You broke your promise to me.” When she didn’t respond, he shook his head with a loud scoff. “You don’t even remember what you promised me.” He let out a sad chuckle. “You promised me that you wouldn’t go out there alone,” he reminded her. “You promised me that you wouldn’t go near that Kryptonite bomb. You looked me right in the eyes, Kara, and you _promised_ me. And then you went, not even a day later,” he shook his head at her, “and did exactly what you promised me you wouldn’t do.”

“Mon-El--”

“No, Kara, I can’t. I can’t stand here and listen to you defend a decision that you stupidly made in the spur of the moment against the wishes and instruction of _everyone_ who cares about you.”

“I’m Supergirl, Mon-El,” she stated, her eyebrows furrowed, “My _job_ is to save people, even when that puts me in danger.”

“Kara, this didn’t just put you in danger. This bomb almost _killed_ you. And it wasn’t even really a bomb! That gas you breathed into your lungs…” He shook his head at her again. “If you--if you would have waited for us to figure it out, we could have easily sent someone else in there. Someone who wouldn’t be killed by Kryptonite gas to disarm it and get rid of it.” His eyes were filling with tears, his face turning red as he turned away, pacing the floor. “How could you be so _reckless_ , so… _careless_ , Kara?”

“Careless?” she questioned, her voice exasperated. “You think I was being careless? It’s _because_ I care that I went out there. I care about this city and the people in it.”

“You had no clue what you were doing, Kara! It could have been a _lot_ worse! You didn’t even know how to stop the bomb when you went out there. You could have accidentally killed yourself: blown yourself up AND this city you love.”

He was shouting and she didn’t understand. She shrugged her shoulders, “I did it to protect you and everyone out there in this city, Mon-El, and I’m not going to apologize for that.”

He sharply spun around to face her. “Do you realize that I sat at your bedside for two whole days and you weren’t waking up? _Two days!_ ” His voice cracked as he continued, “You were cold and pale and fragile and you just laid there and nobody knew what to do. _Nobody_ knew how to help you. It was getting so bad that people didn’t expect you to wake up. People were giving up on you.” He stepped closer to her, standing a mere foot away. “Do you know what that did to me!? Do you understand how unbelievably fucking awful that was for me?!” He had tears slipping from the corners of his eyes, running down his cheeks and he scrubbed the back of his hand along his face to get rid of them.

She could feel her face getting hot, her eyes starting to sting. Her voice was a whisper, “You need to calm down, Mon-El. I’m fine and I’m right here,” she struggled to smile.

“Calm down?! Kara, how am I supposed to calm down when you’re running around against everyone’s instruction and trying to get yourself _killed_? How am I supposed to ignore how dangerous you’re being with your own life?” His hands covered his eyes for a moment, “If I had found you lying there not breathing, Kara…” his voice cracked before trailing off. His hands fell from his eyes and he nearly fell into her as his hands cupped her cheeks. “Kara, I love you so much I don’t think I would have survived that.” He pressed his forehead to hers as he let out a small sob.

She blinked at the tears in her eyes. “You…” she trailed off at his eyes slipped closed. “That’s the first time you said that,” she noted, her voice at a low whisper. She swore she had heard it. Heard it for the first time coming from his mouth.

His eyes flew open. “What?” They looked confused. “Said what?”

“That you love me.”

“I said what?” his eyebrows were furrowed and he was starting to pull away from her.

She smiled, a tear rolling down her cheek without her permission. “You said…you said ‘I love you so much I don’t think I would have survived that’. You love me. You’ve never said that to me before,” she shook her head.

“I don’t, uh…” he released his hold on her cheeks as he took a step back. “I don’t think I said that.”

She furrowed her eyebrows in confusion. “I’m like 99.9% sure that you said it, Mon-El.”

He blinked at her, jaw hanging open slightly and she realized that he was surprised that he had said it -- that it had slipped out. “No…I--”

She sniffled slightly as she steeled herself, “Are you going to take it back now?” She stepped closer to him as he took another step back. “Because I know you said it.”

He didn’t say anything, his eyes falling to her feet.

“It’s okay,” she paused as she nodded, “It’s okay if you didn’t mean it. If it just slipped out and you want to take it back.”

His eyes shot up to hers, his vision clouded with tears. “Of course I meant it,” he sighed heavily. “I’m not…I’m not taking it back. But I just,” he shook his head, “I mean--I feel it, I just didn’t mean to say it. Right now. Like that.” He felt the tears escaping again and he scrubbed at his eyes with his arm, muttering _Shit_ under his breath.

She stepped up to him, her hands lifting and cupping his jaw. “I don’t understand. Are you embarrassed that you said it?”

He shook his head.

“Then what?”

“I just…” his eyes connected with hers. “I didn’t want to say it when I was angry--to say it to prove a point in an argument or something. I wanted to say it because…” he sighed heavily again. “I love you, Kara. And I’ve never said that to a woman before. I’ve never _felt_ that for a woman before, so I’ve never felt like I should say it.” His hands came up and pressed against hers on his face. “I’ve never _wanted_ to say it.” He removed her hands from his cheeks and he held them low at his hips. “And then I’m thinking of how much I love you, and they’re talking about this _Kryptonite_ bomb and for the first time in my life, I was terrified that you would go there and you would get hurt. And then you did!” He clenched his eyes shut. “You did and you almost _died_ and it was right after you promised me that you wouldn’t go there. And I just wonder if I even matter to you--if--if you even thought about me before going out like that. If you even _considered_ my feelings. And it makes me wonder if you even love me back? If this is all just one sided. Because I don’t think I can _be_ with you if this is _that_ one sided, Kara.”

His rambling stopped and his eyes slowly fluttered open to focus on her. She had tears trickling down her face and her lower lip was trembling.

“Mon-El,” she tried, her voice cracking, “I--” she shook her head.

“Kara,” he started with a sigh.

Then her lips crashed into his and his hands tangled in her hair as she pushed him backwards toward her bedroom. His feet tripped on the edge of the area rug, and her foot accidentally kicked the leg of a chair as they stumbled to her bed.

Fingers hastily tore at clothing, underwear being all that remained; teeth nipping, chests bumping as she nudged him backwards. He landed at the side of the bed, sitting on the edge, feet flat on the floor as she landed in his lap.

She wasted no time in sliding her hand into his boxers to grab a hold of his cock, hand tugging firmly as he threw his head back on a groan. Her lips fell to his jaw, kisses trailing along his stubble and down to his neck as her hand slid and squeezed up and down his shaft.

His hands unhooked her bra and removed it before sliding into her panties, gripping her bare ass and pulling her tightly against him, her hand stilling its movements as it became trapped between their bodies.

“Mon-El,” she panted against his lips. “Don’t ever think that,” her forehead fell against his. “Don’t _ever_ think that I don’t think about your feelings. You’re one of the first things I think about when I put on that suit and risk my life. I just have to…I have to put it out of my mind sometimes because it’s my job to protect people.

“Kara,” he groaned as she absentmindedly squeezed his cock while she spoke, his hand reaching for hers and stilling it. She released him and stood to remove her panties as he tugged off his boxers.

She found her place in his lap again, forehead leaning into his. “I love you, too, Mon-El,” she whispered. “I do. So much. Please don’t doubt that.”

“I believe you,” he whispered as she lifted up, aligning him with her centre before sinking down on him, her walls tightly encasing him as his forehead fell to her shoulder. His hands gripped and moved her ass steadily as he assisted her legs in her movements up and down on top of him.

Merely a few minutes into it and they were both almost at their peak, lips melded together as they struggled to breathe against each other.

“Kara,” he panted.

“Hmm," she hummed, eyes clenched shut.

“I love you,” he whispered and her eyes popped open to connect with his teary ones.

“I love you, too,” she nodded, her walls fluttering around his cock, making him groan loudly in her ear.

“I can’t lose you, Kara.”

Her hands grabbed his chin, pulling him to face her directly. “Baby, you’re not going to,” she sighed. “I’m not going anywhere.”

He nodded as his hips lost their rhythm, his thrusts becoming almost frantic.

“Mon-El,” she stroked his hair, pushing it off his forehead. “Let go,” she encouraged, “I’m right here.”

His forehead fell into the crook of her neck as she threaded her fingers through the hair at the back of his head.

“Kara,” he moaned as she flexed her fingers against him, her nails scratching at his scalp.

“It’s okay,” she mumbled against the crown of his head.

He reached a hand between them, his thumb flicking at her clit and she stiffened above him, her walls clamping down on him as she felt her orgasm starting to overcome her. Her knees gave in as she fell on him hard, their pelvises crashing together as he came with a grunt inside of her, his teeth scratching against her shoulder.

They sat in silence for a minute, holding onto each other as they tried to get their breathing back to normal.

“I’m sorry,” he whispered while looking up at her.

She struggled to focus her eyes on his face. “What?”

“I’m sorry,” he repeated.

“For?” she questioned, her forehead crinkling.

“I’m sorry I yelled at you. I was just scared.”

“I know,” she nodded, her hand stroking his cheek. “I won’t do that to you again, Mon-El.” She shook her head. “I won’t break a promise like that again.”

“Thank you,” he sighed.

“I’ll also listen to the DEO agents when they say something is too dangerous. And I’ll be careful. Well,” she stopped, “as careful as a superhero trying to save the world can be.”

He smiled, “That’s all I’m asking for, Kara.”

She shifted closer to him in his lap, her arms locking around his neck, her chest flush with his. “And thank you for telling the truth…about your feelings for me.”

“I should have told you sooner,” he sighed. “I wanted to. I was just waiting for the right time.” He shrugged against her.

“Well, I’m just glad you said it is all. I’m glad I know.” She stood from his lap and he let out a groan as he slid out of her. “Now, I’m going to take a bath,” she stated as she held out her hands to him. He grabbed a hold of hers, their fingers intertwining as he stood" “And I want you to come in with me.”

She turned, placing his hands on her naked hips. His thumbs slid across her waist as he placed a kiss on the back of her shoulder while following her into the bathroom.

“I’d love to,” he said, unable to stop the smile from spreading across his face.

 

 

_END._

**Author's Note:**

> Thanks for reading! I love and appreciate all the kudos, comments and/or prompts you all give, so please leave some! <3


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